BY E. C. ANDREWS. 181 



for the upper courses of our coastal streams, since waterfalls and 

 rapids will then be no more. 



Instances of these interesting phases of river development 

 might be multiplied from the cordillera. 



It appears, then, that probably at some period in Tertiary time, 

 immediately preceding the present cycle, the Queensland coast (as 

 also that of N.S. Wales) ran parallel to, although at a consider- 

 able distance from, the present shoreline, and that shore develop- 

 ment had advanced to the advanced old age stage as a result 

 of long-continued marine erosion and sedimentation. An old 

 upland* curved sympathetically with the coast, and was coeval 

 with it. The evidence goes to show that immediately prior to 

 the great movement obtaining at present, this old land was 

 dissected by subaerial agencies as to its eastern and western 

 portions to a stage of old age. A differential movement 

 was set up, involving such forms of stress as tilting, folding, 

 faulting and warping, the motion varying both from east to 

 west, and from north to south. The pivotal axis was probably 

 an inconstant quantity, although confined in the main to the 

 neighbourhood of the centre of the cordillera. It may be stated 

 here, although the discussion is reserved for a future paper, that at 

 the close of the Cretaceous period a long protracted cjx'le of 

 erosion resulted in the formation of a plain almost at sea-level in 

 the area occupied now by the tableland. An elevation of 1,000- 

 1,500 feet took place in the early Tertiary period ; while the 

 new cycle of development was in a fairly advanced stage, several 

 distinct basaltic outbursts occurred, each separated by long- 

 intervals of time. The plateau was then worn down to the old 

 age stage, when another cycle of elevation intervened, forcing 

 the Cretaceous and Tertiar}^ peneplains an additional 3,000 

 feet above sea-level. Reduction of the plateau was then 

 started afresh by the swiftly falling streams, and after an 

 anastomosing series of canons had been imposed upon the 

 plateau, accompanied by mature or old age coastal develop- 

 ment, a minor cycle of subsidence ensued for the coastal area, of 



* Plateau of erosion. 



